The present invention relates to dc motors with an electronic commutation and more particularly relates to the structure thereof.
DC motors with an electronic commutation comprise, among other elements, a housing which contains a wound armature from which a shaft extends. The commutation means for this armature, instead of being formed conventionally by an electromechanical device comprising a ring and brushes, are in this case formed by an electronic device with a control module connected to the fixed armature of the stator.
This type of motor usually presents delicate problems of manufacture, construction and assembly.
Indeed, windings must be formed and disposed in slots of the armature, then the ends of the wires of the winding coils of this armature must be connected to the electronic circuit of the control module, and, lastly, it must be possible to dissipate the heat of the power components of the electronic circuit of the control module.
A first source of difficulty is the formation of the winding coils of the armature when it is desired to proceed automatically and directly on the armature.
To ensure the connection of the ends of the wires of the winding coils to the electronic circuit of the control module, the ends of the wires are usually soldered to terminal connectors which are, or are not, directly associated with the electronic circuit Most of the time, bearing in mind the configuration of the structure of the motor, this soldering can only be carried out manually This is all the more delicate because each winding coil on principle requires two solders. Such an operation, which is particularly difficult to automate, is another source of difficulty since it requires very high skill and is time-consuming. Such solders are subject to faulty contacts.
Another source of difficulty is related to the existence of the electronic device which very often comprises power components which must be cooled so as to avoid their heating which would otherwise be destructive. This often leads to dividing up the electronic circuit in such manner that some of its components are no longer on the substrate of the printed circuit itself but are mounted directly on the housing so as to dissipate heat and improve ventilation. It will be easily understood that this also complicates the mounting and assembling operations and is also a source of bad workmanship.
Documents FR 89-11 771, FR 90-03 826 and FR 90-11 702 --(corresponding to French Patent Nos. 2651933, 2660124 and 2667202, respectively) disclose solutions-for overcoming this type of difficulties.
Another source of difficulty is also related to the design of the mechanical structure of this type of motor which is generally such that it is not possible to proceed automatically in its assembly and its mounting by simple operations with non-complex kinematics easy to carry out with the aid of robots or programmable automatons, since the
components are numerous and have complicated configurations.